The present invention relates to a novel type of assembly of single- or multi-channel elements. The invention applies to filtration, separation or the bringing of liquid or gaseous fluids into contact and for example, to microfiltration, ultrafiltration, nanofiltration, pervaporation, reverse osmosis, and can apply to (bio)membrane reactors, to gas diffusers, to liquid or gas/liquid or gas contactors, or to catalysis, or to fuel cells.
Several types of single- or multi-channel (filtering) element assemblies are already known.
The elements can firstly be arranged individually in a casing and then occupy predetermined positions. The element is held in place by two support points located at the ends of the part. Depending on the length of the single- or multi-channel element, the distance between these two points of support can be significant. The disadvantage of this system resides in this distance between the two points of support which make it obligatory to use elements which can withstand significant mechanical stresses. This first type is generally employed falls single- or multi-channel ceramic membranes well suited to withstanding mechanical stresses.
In order to reduce the distance between the points of support, one or several bracing members or distance pieces can be employed. These are intended to improve mechanical strength of the set of elements. The bracing members are located perpendicularly to the length of the elements. The bracing members have holes which are used to position the elements and, like in the case above, each element occupies a well defined position. The use of bracing members makes it possible to improve mechanical strength but creates enormous disadvantages arising from the pre-defined positions of the elements in the assembly. Firstly, any deviation from straightness along the length of the elements proves to be a problem at each bracing member. Then, problems of industrial implementation are present. Indeed, it is very difficult to assemble a large number of elements as this involves sliding the elements one by one through the different holes of the bracing members. Additionally, assembling the filtering elements one by one is difficult with fragile filtering elements. The only filter modules currently known using bracing members are modules employing carbon membranes which have been reinforced with fibers arranged on the outside of the membranes. In the case of fragile filtering elements, it is impossible to insert, in practical terms, a large number of elements into a bracing member. Another disadvantage of this system of assembly originates from the barrier created by these bracing members which disturbs the flow of fluid which has been treated or is to be treated.
In one embodiment generally applied to organic fibers, the elements can be arranged in the form of a sheaf or bundle. These elements are then joined at the end by a potting operation. This bundle represents a cartridge which is then positioned inside the casing. Unlike the cases above, the elements do not have well defined positions but the complete bundle occupies a given space. If this bundle which is employed with organic membranes satisfies the constraints for industrial implementation (at the manufacturing stage), it in no way improves the mechanical withstand strength of the membranes. The distance between the points of support is in effect too large in the case of single- or multi-channel elements which are mechanically fragile. In this case of organic fibers, they are frequently reinforced at their xe2x80x9cfootxe2x80x9d, in other words at the bond between the fiber and the potting compound. This is possible since the organic fiber is made from a polymer which can be reinforced with another polymer which is stronger or harder, such as for example with a thermoplastic polyurethane (TPU). The solution can however not be transposed to filtering elements which are more fragile such as those of ceramic, as there is no material in existence able to fulfil the function played by the TPU above. Additionally, in this system of assembly the space between the filtering elements is not determined. This lack of determination has a negative effect on the flow of fluid to be treated or which has already been treated and limits the performance of the assembly in the form of a bundle.
None of the assembly systems of the prior art is perfectly suited to the assembly of a large number of single- or multi-channel mechanically-fragile filtering elements. None of the cases cited above neither teaches nor suggests the present invention, suited to mechanically-fragile elements, and providing a solution for overcoming the various disadvantages discussed above.
The invention provides a novel type of assembly of elements for filtration, separation or reaction, applicable to any type of element (whether single- or multi-channel), notably those which are mechanically fragile, an assembly in which said elements are linked together in order to form a sheet of elements.
The invention consequently provides a sheet of elements for filtration, separation or reaction, in which the elements are joined together by inter-element linkages.
According to one embodiment, the sheet exhibits the three following dimensionless numbers:
A: Number of inter-element linkages per filtering element comprised between 1 and 20,
E: Number of filtering elements per inter-element linkage comprised between 2 and 2000,
N: Total number of filtering elements comprised between 10 and 2000.
According to one embodiment of the sheet:
A is comprised between 2 and 5;
E is comprised between 3 and 700;
N is comprised between 10 and 300.
According to one embodiment of the sheet, the elements are directly linked to 4 other elements at the most.
According to one embodiment, the inter-element linkages are constituted by linking units joining the elements together and connected to the latter by fastening means.
According to one embodiment, in the sheet, the linking units connect the elements pairwise.
In one embodiment, the inter-element linkages are linear.
In another embodiment, the inter-element linkages are branched.
The inter-element linkages can make, with respect to the axis of the elements, an angle of 30 to 150xc2x0, preferably between 60 and 120xc2x0.
According to one embodiment, the inter-element linkages are in elastomer and/or thermoplastic polymer.
In one embodiment, the inter-element linkages are in ceramic cement.
In a further embodiment, the inter-element linkages are attached to the elements by mechanical and/or physico-chemical means.
The inter-element linkages and the fasting means can be made of the same material.
The elements can be single- or multi-channel elements.
According to one embodiment, said elements are ceramic fibers.
According to one embodiment, said sheet is rigid.
According to another embodiment, said sheet is flexible.
In a further embodiment, said sheet is flat.
The invention also provides a method for preparing a sheet comprising the steps of:
(i) placing the filtering elements on a suitable support;
(ii) linking said elements by means of inter-element linkages.
Step (ii) can comprise a first sub-step comprising applying an inter-element linkage precursor and a second sub-step comprising transforming said precursor into said linkage.
The method for preparing a sheet can comprise the steps of:
(i) arranging an inter-element linkage precursor on a suitable support;
(ii) arranging the filtering elements on said precursor;
(iii) connecting said elements to said inter-element linkages by transforming said precursor into said linkage.
According to one embodiment of the method, the transformation of said precursor is carried out by polymerization.
The invention also provides a filtration, separation or reaction module comprising at least one sheet according to the invention.
This module can comprise two end ottings in epoxy, with said inter-element linkages being in elastomer and/or thermoplastic polymer.
In another embodiment, it comprises two end pottings in ceramic cement with inter-element linkages in elastomer and/or thermoplastic polymer.
In a further embodiment, the module comprises two end pottings in ceramic cement, with the inter-element linkages in ceramic cement.
The module can comprise at least two sheets placed one above the other.
In a further embodiment, the module comprises at least one wound sheet.
The invention also provides a method for preparing a module according to the invention, comprising the steps of:
(i) preparing at least two sheets by the method according to the invention;
(ii) placing these sheets one above the other; and
(iii) potting the ends thereof.
The method for preparing a module can comprise the steps of:
(i) preparing at least two sheets by a method according to the invention;
(ii) applying, to at least one of said sheets, an inter-element linkage precursor and placing said at least one second sheet thereover;
(iii) transforming said precursor into an inter-element linkage; and
(iv) potting the ends thereof.
The method for preparing a module can also comprise the steps of:
(i) preparing at least one sheet by the method according to the invention;
(ii) winding said sheet or sheets about itself or themselves; and
(iii) potting the ends thereof.
The method for preparing a module can also comprise the steps of:
(i) preparing a sheet by the method according to the invention;
(ii) applying to said sheet an inter-element linkage precursor;
(iii) winding said sheet about itself;
(iv) transforming said precursor into an inter-element linkage; and
(v) potting the ends thereof.
The method for preparing a module can also comprise the steps of:
(i) preparing at least two sheets by the method of the invention;
(ii) applying, to at least one of said sheets, an inter-element linkage precursor;
(iii) winding said sheets about themselves;
(iv) transforming said precursor into an inter-element linkage; and
(v) potting the ends thereof.
The invention will be described in a more detailed fashion below with reference to the attached drawings.